Even in the upper echelon of Patek Philippe’s catalog of great perpetual calendar watches, the 3940 remains unparalleled. Its production spanned three continuous decades, from 1985 to 2007, one of the longest production runs in Patek’s history. It was exclusively available in precious metals, first in yellow gold, and later in rose and white gold, as well as some platinum versions, and its flowing curves and 36mm size both alluded beautifully to Patek’s legacy of elegant perpetual calendars.